A redundancy system in the interface between a wireless and packet-based telecommunications network.
A typical cellular communication system is comprised of multiple cell sites covering an intended geographic region. Referring to FIG. 1, a wireless telecommunications system 15 communicates with a mobile unit, or Mobile Node MN1 65, via wireless communications signal 60. The cellular communications to MN1 65 are supported by at least one antenna 7, a transceiver XAN 9, and a base station transceiver substation 45 (xe2x80x9cBTSxe2x80x9d).
The transceiver XAN 9 is coupled to the BTS 45 via signal line 10, and the transceiver XAN 9 is coupled to antenna 7 via signal line 8. Radio signal 60 represents the wireless signal transmitted from antenna 7 to Mobile Node MN1 65. The Mobile Node MN1 65 supports the voice and data communication from a subscriber, mobile unit user, or a mobile node in a particular cell cite service area.
The BTS 45, sometimes called the base station, provides wireless communications coverage within a cell site service area by performing base station processing to support the common air interface transmission to the Mobile Node MN1 65. Mobile Nodes MN1 65 in the cell site area communicate through the antenna 7 and transceiver 9 combination thereby supporting the radio communication to the BTS.
Looking at FIG. 1, the BTS 45 is coupled to the GPRS network 40 via signal line 43. The GPRS network 40 also includes a Serving GPRS Support Node SN1 59 and is coupled to the remainder of the GPRS network 40 via signal line 57. The GPRS network 40 also includes other Support Nodes SNn 55, which are coupled to the remainder of the GPRS network 40 via signal line 45. Support node SN1 59 is coupled to a Gateway GPRS Support Node GN1 72 via signal lines 60 and 61, respectively. Gateway Node GN1 72 is also part of the GPRS network 40 and is coupled to a Packet-Based Network 80 via signal line 74. The Patent-Based Network 80 can include the Internet or any other type of IP packet-based system. Further, the Packet-Based Network 80 can also include an interface to non-packet-based networks such as the Public Switchboard Telephone Network. In FIG. 1, GN 72 is the interface between the wireless telecommunications network 15 and the Packet-Based Network 80.
A more detailed view of various telecommunications networks can be seen in FIG. 2A. FIG. 2A shows a General Packet Radio Service (GPRS) wireless telecommunications network comprising a GPRS1 network 140 coupled to a first Radio Access Network RAN1 130 via communication line 135. The RAN, 130 is coupled to transceiver XAN1 120 via communication line 125. The transceiver XAN1 120 communicates with a first Mobile Node MN1 110 via wireless communications signals 115.
The GPRS1 network 140 comprises an Home Location Register Support Node (HLR) 144 coupled to the Servicing GPRS Support Node (SGSN) 142 via signal line 152. The GPRS1 network 140 also comprises a Call Server Node (CSCF) 146 coupled to an Gateway GPRS Support Node (GGSN) 148 via signal line 160. The GGSN 148 is coupled to the SGSN 142 via signal line 150, and the CSCF 146 is coupled to the HLR 148 via signal line 152. A network interface Gn 150 is located on signal line 151 between the GGSN 148 and the SGSN 142.
The GPRS1 network 140 is coupled to an Internet Protocol/Multimedia (IP/MM) network 200 via signal line 165. An external interface Gi 161 is located on signal line 161 between the GGSN 148 and the IP/MM 200. The GPRS, network 140 is also coupled to a Media Gateway MGW 180 via signal line 170. An external interface Gi 171 is located on signal line 170 between the GGSN 148 and the MGW 180. The MGW 180 includes a Media Gateway Control Function (MGCF) Node 185 coupled to signal line 170 via signal line 190. The MGW 180 is coupled to a Public Switched Telephone Network (PSTN) 210 via a signal line 178. A PSTN telecommunications device 212 is located on the PSTN network 210, and the PSTN device 212 is coupled to the MGW 180 via signal line 178.
A second GPRS2 network 235 is located on the Public Land Mobile Network (PLMN) 225. The PLMN 225 is coupled to the GPRS1 network 140 via signal line 220. The GPRS2 network 235 includes a second Gateway GPRS Support Node (GGSN2) 230, as well as a second HLR2 232, SGSN2 233, and CSCF2 234. These elements in the GPRS2 network are coupled to each other via signal lines 237 as shown in FIG. 2. The GPRS2 network 235 in the PLMN 225 is coupled to a second radio access network (RAN2) via signal line 240. The RAN2 245 is coupled to a transceiver XAN2 255 via signal line 250, and the XAN2 255 communicates with a second Mobile Node MN2 270 via wireless communication signals 260.
While represented in greater detail, the interface components between the wireless network and the packet-based network in FIG. 2 include the network interface Gn 151, the GGSN 148 and the external interface Gi 161 or Gi 171. These interface components cooperatively translate communications in the wireless communications format (e.g. GPRS format) to the packet-based communications format, and vice versa.
Telecommunication networks can be complex networks that establish and maintain connections between two or more telecommunication devices. Because wireless communications transmitted on the wireless network are substantially different than the packet-based communications on the Packet-Based Network 80 shown in FIG. 1, an interface between these different systems plays a very important role in the effective performance of the system. During the transmission of communications on these systems, the user establishes context information (e.g. PDP Context Information) with various support nodes on the system. The GGSN 148 will assist the network in locating a system user and their network association. The context information on the system can include state information, identification information, and address information for a particular user during a communications session. The addressing and context information will support the transmission of information by providing necessary context information on routing and addressing. The GGSN will modify message formats and re-configure the communication signals based, in part, on this context information. If a nodal failure occurs at GGSN 148 or another support node, the context information will be lost without an effective redundancy scheme.
One redundancy scheme for a GGSN interface available in the prior art includes the system shown in FIG. 2B. In this system, signal line 295 is coupled to Router, 300, which in turn is coupled GGSN1 315 and its redundant GGSN1xe2x80x2 345 via signal lines 310 and 335, respectively. The GGSN1 315 and its redundant GGSN1xe2x80x2 345 are coupled to Router2 355 via signal lines 320 and 350, respectively. Router2 355 is coupled to signal line 360. Signal lines 295 and 360 transmit and receive communication signals on the Router1 300 and Router2 355.
Each router will use GGSN1 315 as its main GGSN unless, or until, there is a support node malfunction, nodal failure, or shut-down of this support node. During normal operations, the GGSN1 315 will retain the context information for communications transmitted through the interface shown in FIG. 2B. The GGSN1 315 will automatically place a back-up of all context information it receives to the redundant GGSN1xe2x80x2 345 upon the receipt of each communication. The automatic, and constant, back-up filing in the redundant GGSN1xe2x80x2 345 occupies a significant amount of computing capacity of the support node GGSN1 315. If the computing capacity associated with filing back-up information could be used in connection with operational tasks, the overall efficiency of the interface system would be increased substantially. The back-up operations are shown by arrows 330 in FIG. 2B.
If, or when, the support node GGSN1 becomes non-operational, the routers 300 and 355 will be informed of the status or detect that non-operational status independently. Thereafter, the routers will begin directing their communications to the redundant support node GGSN1xe2x80x2 345. If possible, the back-up context information in the redundant GGSN1xe2x80x2 345, as supplied by GGSN1 315, can be used to provide continuity in the connection session. Even with the periodic back-up information, however, re-routing the call connection through the redundant GGSN1xe2x80x2 345 may not be a seamless connection. In fact, context information may be lost or not available in the redundant GGSN1xe2x80x2 345 to allow the call connection to continue. In this situation, the system user would have to re-establish the connection and provide context information to the redundant support node GGSN1xe2x80x2 345. Obviously, requiring the system user to re-establish their connection, and context information, would have a visible impact on the system performance.
As such, it is highly desirable to provide redundancy on important areas of the telecommunications system, but the redundancy scheme used with the system should minimize the overhead burden on the system components and increase the overall efficiency of the system. Further, the redundancy scheme should minimize the need to re-establish the user connection, and associated context information, in a redundant GGSN after a nodal failure or non-operational status. As such, an effective and efficient redundancy scheme is necessary to ensure that the interface system remains operational and performs as efficiently as possible.
The invention provides a passive redundancy system for context information on a GGSN interface. The system positions broadcast HUB routers on each side of the GGSN, and the system also uses one additional back-up GGSN positioned with each GGSN. The back-up GGSN monitors all communications traffic transmitted to the primary GGSN through the communications from the broadcast HUB nodes coupled to the primary and back-up GGSNs. In this manner the primary GGSN does not have the overhead burden of constantly updating the context information into a redundant GGSN.
Because the back-up GGSN receives and retains the same context information as the primary GGSN, the back-up GGSN can assume responsibility for the communications traffic through the interface in a relatively seamless manner. That is, the back-up GGSN retains the same context information as the primary GGSN because the back-up GGSN monitors traffic, including context information, from the broadcast HUB routers; and, if the primary GGSN becomes non-operational, the back-up GGSN can assume the responsibilities for providing context information just like the primary GGSN without any incurring disconnections, losses of services, or needs to re-establish the connection by the system user.